Research Of Normalization Of Expression Data For Gene Chip

With the rapid development of molecular biological and computational technologies, the implement of HGP and achievement of HGD show that modern life science research has entered the post-geomic era. The DNA microarray is capable of profiling the expression levels of many genes simultaneously, and is a promising technology for the research of gene interaction. A basic question in analyzing cDNA microarray data is normalization. The purpose of normalization is to remove systematic bias which exist through the experiment in the observed expression values by establishing a normalization curve across the whole dynamic range. It's important for the next data analyzing.In the article, we have made some changs and improvements to the Lowess normalization and TW-SLM normalization proposed by Huang, J. et al. (2005) respectively, in view of robustness. for example, we consider locally weighted least absolut deviation regression instead of locally weighted least squared in the Lowess normalization. Also, We use the variance estimated by TW-SLM normalization as the weights for the next weighted least squared. We also conduct simulation studies to evaluate the above-mentioned normalization methods.